Welcome to my blog. I found a malicious code that was added into the bcdedit.exe file. Due to infection by malicious code, the file contents changed. The MD5 value of the infected file is: 47ca5ecbd4eda15f14cc2bef8036ed8a, and the file size is:
315 K ( 322,560 bytes )

Risk level of malicious code

( 3 stars by 167 users )

Behavior of malicious code ( 331 votes ) If you know more this malicious code, please vote. We sincerely hope you may share your information with other computer users and help them.

1. Infect file

11.78% (39)

2. Intentionally destroy data

12.99% (43)

3. Steal personal privacy

12.69% (42)

4. Infect other computers through the Internet

12.08% (40)

5. Install the backdoor program so that the computer is controlled remotely

15.41% (51)

6. Cheat or threaten users to buy something

14.8% (49)

7. Download and install other programs without permission in the background

9.37% (31)

8. Pop up various advertisements and induce users to click

10.88% (36)

Binary Code Analysis:

When the program runs, the PE loader will try to load the file to 0x01000000 in the virtual address space, Address Of Entry Point: 0x000125F0. This file has 5 SECTION.

DOS Header

DOS Stub...

NT File Signature

NT HEADER

FILE HEADER

OPTIONAL HEADER

Data Directory

.text SECTION #1

.data SECTION #2

.rsrc SECTION #3

.reloc SECTION #4

wiovapz SECTION #5

Name

Virtual Size

Virtual Address

Size Of Raw Data

Pointer To Raw Data

Pointer To Relocations

Pointer To Linenumbers

Number Of Relocations

Number Of Linenumbers

Characteristics

SECTION #1

.text

0x00023DD4

0x00001000

0x00023E00

0x00000400

0x00000000

0x00000000

0x00000000

0x00000000

0xE0000020

SECTION #2

.data

0x00000734

0x00025000

0x00000400

0x00024200

0x00000000

0x00000000

0x00000000

0x00000000

0xC0000040

SECTION #3

.rsrc

0x00021C58

0x00026000

0x00021E00

0x00024600

0x00000000

0x00000000

0x00000000

0x00000000

0x40000040

SECTION #4

.reloc

0x00008E00

0x00048000

0x00008800

0x00046400

0x00000000

0x00000000

0x00000000

0x00000000

0xE0000060

SECTION #5

wiovapz

0x00001000

0x00051000

0x00000000

0x0004EC00

0x00000000

0x00000000

0x00000000

0x00000000

0xC0000000

About this malicious code

This malicious code is a 32-bit program that infects an EXE file. When the file is run or the file is loaded, the malicious code in the file is run first. Later, this malicious code also infects the following files:

Tip: There is something I must emphasize. The file names listed above are infected by malicious code. It does not mean that all files named by these names are malicious files. It is inaccurate to determine whether a file is a malicious program based on its file name.

Tip: The code of most malicious files is fixed, rarely changed, which means, this type of malicious files regardless of which computer they are in, will copy themselves into the pre-set path, so we can go to the path listed above to find this file, and there is a great chance to find it.

Are all the files with the same file name listed above and with the same path malicious files?

Of course not. The file name is just the identification of the file. Strictly speaking, the file is modified by malicious code.

The following are methods commonly used by malicious code in order to confuse users:

• Deliberately modify their own file name to some system file name, or some well-known software name.

• Generate malicious files in the system folder or in the installation folder of some well-known software, and even name their own folder with an antivirus software name (actually the user did not install this antivirus software). In fact, these malicious files are not system files, nor part of the famous software.

For example, one of the most common system file names is: explorer.exe, and under normal circumstances, the system only has an explorer.exe process. When you open the Task Manager and find that there are two or more explorer.exe processes, it is likely the camouflage of some malicious viruses. As shown in the following figure, there are two explorer.exe processes in Task Manager.

When I find the path where the file is located, it will be clear that the real explorer.exe system file is located under "C:\ Windows\", and the malicious file that pretends to be system process is under the other path.

The running status of the bcdedit.exe file that is infected with malicious code:

Take up memory 980KOccupy CPU resources between 39% - 58%Run the program with the Administrator permissions.

At runtime, 4 Windows system files, 0 external files (not owned by the Windows system), are called

Windows system files

File name

Number of calling functions

KERNEL32.dll

44

msvcrt.dll

57

ntdll.dll

53

ADVAPI32.dll

3

Not owned by the windows system

File name

Number of calling functions

In general, the most accurate way to determine if a file is a malicious file is to analyze its code and see what happens when these functions are called while the program is running. Does it have malicious behavior (destroying data or stealing data)? I have listed the functions called by this file and some internal data, but there is too much data, I can't show them all here. →Click here← to see the full binary code analysis page.

bcdedit.exe runtime behavior analysis

The KERNEL32.dll dynamic link library is loaded and the functions in the file are called: ( Kernel32.dll is a very important 32-bit dynamic link library file in the Windows operating system. It is a kernel-level file. It controls the system's memory management, data input and output operations and interrupt handling. When the Windows operating system starts, kernel32.dll resides in a specific write-protected area of memory, so that other programs cannot occupy this memory area. )

WriteConsoleW: Writes a character string to a console screen buffer beginning at the current cursor location.

GetConsoleMode: Retrieves the current input mode of a console's input buffer or the current output mode of a console screen buffer.

DeviceIoControl: Sends a control code directly to a specified device driver, causing the corresponding device to perform the corresponding operation.

CreateFileW: Creates or opens a file or I/O device. The most commonly used I/O devices are as follows: file, file stream, directory, physical disk, volume, console buffer, tape drive, communications resource, mailslot, and pipe. The function returns a handle that can be used to access the file or device for various types of I/O depending on the file or device and the flags and attributes specified.

GetModuleFileNameW: Retrieves the fully qualified path for the file that contains the specified module.

GetProcAddress: Retrieves the address of an exported function or variable from the specified dynamic-link library (DLL).

LoadLibraryW: Loads the specified module into the address space of the calling process. The specified module may cause other modules to be loaded.

UnhandledExceptionFilter: An application-defined function that passes unhandled exceptions to the debugger, if the process is being debugged.

GetCurrentProcess: Retrieves a pseudo handle for the current process.

TerminateProcess: Ends the calling process and all its threads.

GetSystemTimeAsFileTime: Retrieves the current system date and time. The information is in Coordinated Universal Time (UTC) format.

GetCurrentProcessId: Retrieves the process identifier of the calling process.

GetCurrentThreadId: Retrieves the thread identifier of the calling thread.

GetTickCount: Retrieves the number of milliseconds that have elapsed since the system was started, up to 49.7 days.

QueryPerformanceCounter: Retrieves the current value of the performance counter, which is a high resolution (<1us) time stamp that can be used for time-interval measurements.

GetModuleHandleA: Retrieves a module handle for the specified module. The module must have been loaded by the calling process.

SetUnhandledExceptionFilter: Enables an application to supersede the top-level exception handler of each thread of a process.

InterlockedCompareExchange: Performs an atomic compare-and-exchange operation on the specified values.

InterlockedExchange: Sets a 32-bit variable to the specified value as an atomic operation.

GetLastError: Retrieves the calling thread's last-error code value.

CreateFileMappingW: Creates or opens a named or unnamed file mapping object for a specified file.

The ADVAPI32.dll dynamic link library is loaded and the functions in the file are called: ( Advapi32.dll is part of a high-level API application interface service library that contains functions related to object security, registry manipulation, and event logging. It is generally located in the system directory: \WINDOWS\system32\ )

RegQueryValueExW: Retrieves the data associated with the default or unnamed value of a specified registry key.

The following files have been identified as malicious files. Some files are variants of bcdedit.exe; some files are another type of malicious file, but use the same file name as bcdedit.exe.

It is a simple and effective way to determine whether a file is a malicious file by a hash value, which has lower false detection rate than the "static signature" method. So, if the MD5 value of a file on the computer is the same as the MD5 value listed below, then it is sure that the file is a malicious file.

This is my analysis results to the code of each malicious below, mainly provided to industry professionals who engage in the maintenance of computer security. If you are interested, you can also have a view, but it may require certain computer knowledge.

This is free virus detection software, and it can be well compatible with many well-known anti-virus software, so users do not have to uninstall anti-virus software on the computer.

It is "environmentally friendly" for computers. After downloading, it can be used by decompression and without installation. In the process of running, it will not write any information to the registry, nor create any new files to the Windows folder of the system disk. When you do not need it, you can delete it. It will not leave any spam information on your computer.

When you find your operating system is abnormal, and the file name listed above appears in the Task Manager, or there are several processes in running with the same name as the core file name, it is best to download the anti-virus software to check your system.

Online detection of bcdedit.exe

If you don't know if bcdedit.exe is infected with malicious code on your computer, you may also use online scan tool.

• Use the following online detection function to check the file.

• Enter the file name, or file MD5, for the query.

• You can also scan a file online. Click the "Upload File" button, and then click the "submit" button, to immediately detect whether the file is a virus. (Tip: The maximum size of the file uploaded cannot exceed 8MB)

How do I use the T21 engine for online scanning?

T21 can detect unknown files online, mainly using "behavior-based" judgment mechanism. It is very simple to use T21.

1. Click the "Upload File" button, select the file you want to detect, and then click "Submit".
2. The next step is to wait for the system to check, which may take a little time, so please be patient.
3. When the T21 scan engine finishes detection, the test results are immediately fed back, as shown below:

• If you suspect that there are malicious files on your computer, but you cannot find where they are, or if you want to make a thorough check on your computer, you can download the automatic scanning tool.

If you want to know what kind of T21 system is, you can click here to view the introduction of T21. You can also go to the home page to read the original intention and philosophy of my development of T21 system.

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